Cranial burr hole plug and insertion tool

ABSTRACT

A cranial burr hole plug with an insertion tool and method of implantation is provided. The burr hole plug includes a shell; a collet interlocked within the shell; a clamp compressing the collet around an elongated medical device exiting the skull of a patient, such as a catheter or lead; and a cover over the clamp, collet, and shell. The insertion tool inserts the collet within the shell and locks the collet around the clamp. The method of implantation includes inserting the burr hole plug components in a cranial burr hole using the insertion tool and securing the exiting medical device without disturbing the position of the medical device.

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/403,787, filed Aug. 14, 2002, which applicationis incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to methods and apparatuses for securingelongated medical devices such as catheters or leads within a cranialburr hole.

BACKGROUND OF THE INVENTION

Deep brain stimulation (DBS) and other related procedures involvingimplantation of leads and catheters are increasingly used to treatParkinson's disease, dystonia, essential tremor, seizure disorders,obesity, depression, restoration of motor control, and otherdebilitating diseases. During these procedures, a catheter, lead, orother medical device is strategically placed at a target site in thebrain. The body of the device then exits through a burr hole cut in theskull. The device must be secured as it exits the skull so as to preventmovement of the device from the precise target site in the brain, andthe burr hole must be filled.

Current burr hole plugs placed under the skin of a patient's head areunduly large and unsightly. Further, many current burr hole plugs do notadequately hold the exiting device in place; some force the device tobend at a right angle at the exit without any protection which makes thedevice vulnerable to fracture or short circuit. During placement ofcurrent burr hole plugs, the exiting device often moves from its precisetarget site in the brain. After placement of current burr hole plugs,the device may migrate over time and will require additional surgicalprocedures to correct the problem.

Due to a lack of adequate burr hole plugs, many physicians attempt tocompensate by securing the device to the skull with sutures and clampingscrews, and then filling the burr hole with cyanoacrylate or bonecement. Securing the device with sutures and clamping screws subjectsthe patient to unnecessary human error. Further, suturing and clampingare cumbersome and time consuming steps. Filling the burr hole withcyanoacrylate or bone cement is messy and permanently locks the deviceinto place, preventing easy access for future necessary procedures.

There is, therefore, a need to provide a relatively small burr hole plugthat, without disturbing the position of the device at the target sitein the brain, adequately and permanently secures a medical device suchas a catheter or lead exiting a burr hole at a gradual angle, butremains accessible for future procedure. Further, there is a need toprovide a method of implanting a burr hole plug that mitigates humanerror and permits safe and efficient implantation.

SUMMARY OF THE INVENTION

The present invention addresses the above and other needs by providing aburr hole plug, a method of implanting the burr hole plug, and aninsertion tool. The burr hole plug includes a shell, a collet, a clamp,and a cover. The burr hole plug is smaller than most currently availableburr hole plugs. The burr hole plug is installed and secures the exitingdevice with simultaneous 360° radial pressure from the collet portion ofthe burr hole plug, thus avoiding disturbance of the position of amedical device at the target site in the brain. The clamp mechanicallylocks the collet around the body of the medical device without exposingthe medical device to pulling, pushing, or twisting forces that couldcause unwanted displacement of the medical device from its target sitein the brain. The collet simply clamps the medical device from alldirections through radial force. The collet, including all other partsof the burr hole plug, is capable of being mechanically unlocked anddisassembled to release the medical device and perform any needed futureprocedures. The device is able to exit the brain at a gradual anglethrough a conical chamber within the collet, through the tip of theconical chamber where the collet grips the device, and out fromunderneath the protective cover placed over the collet and clamp.

The method of implantation includes inserting the shell that is sized tofriction fit against the inner circumference of the burr hole;interlocking a collet within the shell; placing a clamp over the collet,which clamp compresses the collet as the clamp rotates and interlockswith the shell; and placing a cover over the clamp, collet, and shell.Certain portions of the burr hole plug may be inserted separately orsimultaneously using an insertion tool tailored to maximize theefficiency of implantation.

This summary should not be taken in a limiting sense; the scope of theinvention should be determined with reference to the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will be moreapparent from the following more particular description thereof,presented in conjunction with the following drawings wherein:

FIG. 1 shows an exploded view of a burr hole plug;

FIG. 2 shows an exploded view of an alternate embodiment of a burr holeplug;

FIG. 3 shows an isometric top view of a shell;

FIG. 4A shows an isometric top front view of an alternate embodiment ofa shell;

FIG. 4B shows an isometric bottom front view of the shell shown in FIG.4A;

FIG. 5A shows an isometric front view of a collet;

FIG. 5B shows an isometric rear view of the collet shown in FIG. 5A;

FIG. 6 shows an isometric view of a collet with a side slot;

FIG. 7 shows an isometric view of a clamp;

FIG. 8 shows an isometric top view of a cover;

FIG. 9 shows a cross-sectional view of a cover with pin holes;

FIG. 10 shows an isometric side view of an insertion tool;

FIG. 11 shows an isometric top view of an integrated shell-collet; and

FIG. 12 shows an exploded view of the insertion tool with an integratedcollet-clamp for insertion.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description includes the best mode presently contemplatedfor carrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined with reference to the claims.

The present invention is a burr hole plug, an insertion tool, and amethod for implanting the burr hole plug.

As shown in FIG. 1, the burr hole plug has four main components: a shell100, a collet 200, a clamp 300, and a cover 400. The burr hole plug, andits components, can be modified to match any shape or size of burr holein the skull.

FIG. 2 shows an alternate embodiment of the burr hole plug with fouralternate main components: a shell 100′, a collet 200′, a clamp 300′,and a cover 400′. Shell 100′ and cover 400′ and their various alternateembodiments may be used with collet 200 and clamp 300 of FIG. 1 andtheir various alternate embodiments to form a number of alternate burrhole plug combinations. Similarly, shell 100 and cover 400 of FIG. 1 andtheir various alternate embodiments may be used with collet 200′ andclamp 300′ and their various embodiments to form a number of alternateburr hole plug combinations.

As shown in FIG. 3, shell 100 forms the main part of the burr hole plugof FIG. 1 and is made from any hard biocompatible material such astitanium, stainless steel, other metals or alloys, or hard polymers.Shell 100 includes a flange 110, at least two interlocking slots 120, alocking base 130, and a body 140. An alternate embodiment of shell 100has a side slot along the full length of shell 100. This permits thealternate embodiment of shell 100 to be inserted into a burr hole aftera medical device is inserted into the brain by sliding the body of themedical device through the side slot as the alternate shell 100 is movedinto place.

Flange 110 prevents shell 100 from being inserted deeper than theexterior surface of the skull. Flange 110 has a medical device exit 111that secures the medical device and permits the medical device togracefully exit the burr hole plug. Alternate embodiments of a medicaldevice exit may include a similar structure such as a channel, hole,bump, tunnel, tube, or gate that secures the medical device and permitsthe medical device to exit.

Shell 100 is either anchored to the skull, anchored to the skull andcover 400 of FIG. 1, or anchored to cover 400 of FIG. 1. Illustrativeembodiments that enable anchoring follow. To anchor shell 100 to theskull, flange 110 includes at least one hole 112 capable of receiving atleast one screw or similar anchoring device such as a fastener, pin,spike, tab, or button. Similarly, flange 110 may include, on itsundersurface, anchoring structures such as at least one fastener, pin,spike, tab, or button that sinks into the skull where there is at leastone corresponding hole (see FIGS. 4A and 4B). To anchor both cover 400and shell 100 to the skull, a corresponding hole and anchoring device ora corresponding anchor on the undersurface of cover 400 engages with atleast one hole 112 on flange 110. To anchor cover 400 to shell 100,flange 110 and cover 400 include at least one other hole (not shown) orat least one other anchoring arrangement using combinable structuressuch as at least one additional screw and a corresponding hole, at leastone button that snaps into a corresponding hole, or at least one ball(see FIGS. 4A and 4B) that friction fits into a corresponding socket(see FIG. 9).

Interlocking slots 120 permit clamp 300 (FIG. 1) to compress and lockcollet 200 (FIG. 1) into shell 100. Other structures capable ofperforming the same function may be substituted for interlocking slots120.

Locking base 130 permits collet 200 (FIG. 1) to interlock with shell 100and avoid rotation. Locking base 130 may include any structure orstructures capable of locking collet 200 from rotating within shell 100such as at least one tab, at least one notch, or at least one gear.

Body 140 fits tightly against the inner surface of the circumference ofa burr hole in the skull so as to avoid any movement of the burr holeplug in the burr hole after implantation. Additional fixation means orstructures may be added to the exterior surface of body 140 to furtherprevent movement. These means or structures may include, e.g., a roughsandpaper-like surface, notches, or bumps (not shown). Further, verticalor horizontal ribs or threads (not shown) on the exterior surface ofbody 140 will help prevent rotation of the burr hole plug in the burrhole or vertical movement of the burr hole plug out of or into the burrhole.

As shown in FIG. 4A, an alternate embodiment of shell 100′ of FIG. 2employs balls 160 as part of the anchoring arrangement between the shell100′ and cover 400′ previously described.

As shown in FIG. 4B, the shell 100′ of FIG. 4A employs pins 170 asstructures for anchoring shell 100′ to the skull as previouslydescribed.

As shown in FIG. 5A, collet 200 of FIG. 1 is made from any hardbiocompatible material such as titanium, stainless steel, other metalsor alloys, or hard polymers. Collet 200 fits within shell 100 of FIG. 1and secures a medical device exiting the brain through a burr hole. Tosecure a medical device, collet 200 includes at least one finger-likegripper 210 and may additionally include at least one cushion 220. FIG.5A shows four finger-like grippers 210 that, when compressed, centrallysecure a medical device using radial force. Alternatively, one“C”-shaped finger-like gripper with a side slot along all or a portionof its length may compress upon itself to centrally secure a medicaldevice using radial force (see FIG. 6). Similarly, one, two, three,five, and any other possible number of finger-like grippers compressupon itself or each other to centrally secure a medical device usingradial force. Cushion 220, although not essential to securing a medicaldevice, helps stabilize the medical device within at least onefinger-like gripper 210 and helps protect the medical device fromdamage. At least one cushion 220 is made from a soft biocompatiblematerial such as a soft polymer like silicone rubber or an elastomer. Atleast one cushion 220 is attached to one or all of finger-likegripper(s) 210 and may be attached at any point on the inside or outsidesurface of finger-like gripper(s) 210 as long as cushion 220intermediates finger-like gripper(s) 210 and the medical device at thepoint of pressure, which is most likely to be at an apex 221 of thecollet 200.

As shown in FIG. 5B, collet 200 has an internal conical surface 230defining an internal conical chamber, an external conical surface 240,at least one side slot 250 along all or a portion of the length ofcollet 200, and a locking base 260. The internal conical chamber permitsa medical device to exit the surface of the brain at any point in theburr hole and subsequently angle toward the apex 221 of the chamberwhere finger-like gripper(s) 210 secure(s) the medical device. At leastone side slot 250 allows at least one finger-like gripper 210 tocompress upon itself. Locking base 260 permits collet 200 to interlockwith locking base 130 of shell 100, and avoid rotation. Locking base 260includes any structure or structures capable of interlocking withlocking base 130 such as at least one tab, at least one notch, or atleast one gear, thus preventing collet 200 from rotating within shell100.

As shown in FIG. 6, collet 200′ of FIG. 2 has a side slot 270 along thefull length of collet 200′ allowing collet 200′ to mount and encircle amedical device at any point along the length of the medical device.

As shown in FIG. 7, clamp 300 of FIG. 1 is made from any hardbiocompatible material such as titanium, stainless steel, other metalsor alloys, or hard polymers. Clamp 300 locks to shell 100 and compressesfinger-like grippers 210 of collet 200. Clamp 300 includes an internalconical surface 310, a side slot 320, at least two pins 330, and holes340 for engagement with insertion tool 900 (FIG. 10). Internal conicalsurface 310 engages with external conical surface 240 of collet 200,thereby compressing finger-like grippers 210 as pins 330 are insertedinto interlocking slots 120 of shell 100 and clamp 300 is rotatablylocked into position on collet 200 and in shell 100. Insertion tool 900(as shown in FIG. 10) engages holes 340 to apply direction androtational force to clamp 300 during locking. Any number of holes 340 orsimilar structures may be used to engage with a corresponding insertiontool. Pins 330 can be any similar structure capable of interlocking withinterlocking slots 120 of shell 100 or similar structures. Pins 330 arepreferably permanently spaced evenly apart in order to counterbalanceeach other, i.e., two pins are preferably spaced 180° apart, three pinsare preferably spaced 120° apart, and so on.

As shown in FIG. 8, plug cover 400 can be made from either a hard orsoft biocompatible material such as titanium, another biocompatiblemetal, a hard polymer, a soft polymer, silastic, an elastomer, or anycombination thereof. Cover 400 has an undercut 410 for slidingunderneath flange 110 of shell 100. Cover 400 also has a slot 420 for amedical device exit. Alternatively, a channel, hole, bump, tunnel, tube,gate, or similar structure may function as slot 420 to allow a medicaldevice to exit. To anchor both cover 400 and shell 100 to the skull, atleast one corresponding hole 430 and anchoring device or a correspondinganchor or other structure on the undersurface of cover 400 engages withat least one hole 112 or other structure on flange 110 of shell 100. Toanchor cover 400 to shell 100, flange 110 and cover 400 may have atleast one other hole (not shown) or at least one other anchoringarrangement using combinable structures such as at least one additionalscrew and corresponding hole, at least one button that snaps into acorresponding hole, or at least one ball that friction fits into acorresponding socket.

An alternate embodiment of a cover is shown in FIG. 9 as cover 400′ ofFIG. 2. Cover 400′ is made of a soft biocompatible material 450, such assilastic. Cover 400′ has holes 460 for receiving anchors attached toshell 100. An alternate embodiment of a cover (not shown) has anexterior of soft biocompatible material and an interior of hardbiocompatible material with anchors attached to the under side of theinterior for engagement with the shell and/or skull.

As shown in FIG. 10, an insertion tool 900 is used to implant a burrhole plug. Insertion tool 900 has a side slot 910 along its entirelength to permit insertion tool 900 to mount and encircle a medicaldevice at any point along its length. Interior conical surface 920engages with exterior conical surface 240 to center collet 200 or collet200′, while at least two ribs 930 engage with at least two slots 250 torotate collet 200 or collet 200′ until locking base 260 of collet 200 orcollet 200′ locks with locking base 130 of shell 100 or shell 100′. Atleast two pins 940 permit insertion tool 900 to engage with at least twoholes 340 and lock clamp 300 or clamp 300′ into place by rotatinginsertion tool 900 and clamp 300 or clamp 300′ simultaneously. Ribs 930and pins 940 are either on opposite ends of the same insertion tool 900or are on separate tools. The body of insertion tool 900 need not becylindrical, but can be take any size, shape, or form as long as it isconstructed of a hard material such as stainless steel and hasstructures such as ribs 930 or pins 940 that are compatible with andcapable of being engaged with collet 200, collet 200′, clamp 300, orclamp 300′.

A method for implanting a burr hole plug includes a combination of thefollowing steps in various orders so that the burr hole plug securelyfastens and protects a medical device exiting the skull. Except whennecessary, only the structures of the burr hole plug of FIG. 1 aredescribed in the following method. However, this method also applies tothe structures of the burr hole plug of FIG. 2 and all other embodimentsof the present invention.

A burr hole is created. Shell 100, which is shaped and sized to form adimensionally close press fit with the internal circumference or surfaceof the burr hole, is positioned and inserted by being pressed into thehole. If desired, shell 100 is fixed or anchored to the skull by smallscrews or other anchoring structures. The target site of the medicaldevice in the brain is located, and the medical device is placed in thebrain. To close the burr hole plug, collet 200 is carefully insertedinto the opening of shell 100 and properly rotated using insertion tool900 to an interlocking position with shell 100. Clamp 300 is thencarefully placed in shell 100 on collet 200 such that pins 330 alignwith interlocking slots 120 and clamp 300 is pressed and rotated usinginsertion tool 900 to an interlocking position with shell 100.Compression and rotation of clamp 300 lock clamp 300 into shell 100 andrestrain the medical device from further movement in the burr hole.

During the process of closing the burr hole plug, the medical device isnot exposed to pulling, pushing, or twisting forces that could cause anunwanted displacement of the medical device from its target site in thebrain. The medical device is simply clamped from all directions throughradial force from the collet. Plug cover 400 is placed on the top of theburr hole and attached securely by sliding undercut 410 under shellflange 110, employing at least one anchoring arrangement describedabove.

Alternately, plug cover 400′ is anchored to shell 100′ and/or the skullusing at least one anchoring arrangement described above. Cover 400 orcover 400′ protects the medical device at the exit and prevents themedical device from fracturing.

As shown in FIG. 11, shell 100 and collet 200, or their correspondingalternate embodiments, are integrated either permanently, such as by aweld or combined mold, or temporarily, such as by adhesive with a weakbond, to form a shell-collet 500. Integrated shell-collet 500 reducesthe number of components for installation thereby reducing the number ofsteps needed in the insertion and closing procedure. The procedure ofinserting a burr hole plug with an integrated shell-collet 500 isessentially the same as the procedure of inserting a burr hole plug witha separate shell 100 and collet 200 except that shell-collet 500 isinserted into the burr hole after the medical device is inserted intothe brain. Integrated shell-collet 500 may have a side slot along itsfull length in order to permit shell-collet 500 to mount and encircle amedical device at any point along the medical device's length.

As shown in FIG. 12, collet 200′ and clamp 300′ may be temporarilycombined or integrated as by a weak adhesive bond 610 to formcollet-clamp 600. Integrated collet-clamp 600 reduces the number ofcomponents individually inserted by insertion tool 900 and thus reducesthe number of steps needed during a burr hole closing procedure. Wheninsertion tool 900 places collet-clamp 600 into shell 100, locking base260 of the collet portion of collet-clamp 600 is interlocked withlocking base 130 of shell 100, insertion tool and the clamp portion ofcollet-clamp 600 are rotated, and weak adhesive bond 610 between thecollet and clamp portions is broken. When bond 610 is broken, individualcollet 200′ remains in a locked position in shell 100′ or shell 100 andclamp 300′ is then rotatably locked against shell 100′ or shell 100 byengaging pins 330 of clamp 300′ with interlocking slots of shell 100′ orinterlocking slots 120 of shell 100. Similar weak adhesive, cohesive,magnetized, or other bonds placed prior to procedure may combine variouscomponents of the burr hole plug, i.e., shell 100′, collet 200′, clamp300′, or cover 400′, with insertion tools for ease of use andimplantation. After the components are placed in locked position, thebond will easily break, allowing an insertion tool to be removed.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

1-20. (canceled)
 21. A burr hole plug, comprising: a shell capable ofbeing inserted in a burr hole of a skull; a collet capable of securing amedical device within the shell when the collet is compressed; and aclamp capable of interlocking with the shell and compressing the collet.22. The plug of claim 21, wherein the shell further comprises a body anda flange along a top opening of the shell body and wherein the body ofthe shell defines a side slot along the full length of the body of theshell.
 23. The plug of claim 22, wherein the body of the shell includesan exterior surface with a fixation means.
 24. The plug of claim 22,wherein the flange of the shell includes a medical device exit.
 25. Theplug of claim 22, wherein the flange of the shell includes an anchor forattaching the shell to the skull.
 26. The plug of claim 21, wherein theclamp includes a side slot along the full length of the clamp.
 27. Theplug of claim 21, wherein the collet includes a side slot along the fulllength of the collet.
 28. The plug of claim 21, further comprising acover capable of covering the shell, collet, and clamp.
 29. The plug ofclaim 28, wherein the cover further comprises an anchor to attach thecover to the skull.
 30. The plug of claim 28, wherein the cover andflange of the shell are configured for being attached to each otherusing an anchoring arrangement, wherein the anchoring arrangement isselected from the group consisting of at least one screw andcorresponding hole, at least one button that snaps into a correspondinghole, or at least one ball that friction fits into a correspondingsocket.
 31. The plug of claim 21, wherein the collet includes an apexand a compressible soft cushion attached to the apex.
 32. The plug ofclaim 21, wherein the collet has an external conical surface, and theclamp has an internal conical surface adapted to engage with theexternal conical surface of the collet.
 33. The plug of claim 21,wherein the shell includes at least two interlocking slots and the clampincludes at least two externally protruding pins adapted to respectivelyengage with the at least two interlocking slots of the shell.
 34. Theplug of claim 21, wherein the shell includes a body with a locking baseand the collet includes a body with a locking base capable ofinterlocking with the locking base of the shell.
 35. The plug of claim21, wherein the shell and the collet are integrated to form ashell-collet.
 36. The plug of claim 21, wherein the collet and the clampare integrated to form a collet-clamp.
 37. The plug of claim 36, whereinthe collet and the clamp are capable of being separated by rotating theclamp relative to the collet.
 38. The plug of claim 21, wherein thecollet includes at least one slot capable of engaging with an insertiontool, and the clamp includes at least one hole capable of engaging withthe insertion tool.
 39. A kit for plugging a burr hole, comprising: theplug of claim 21, the collet further including a plurality of slots,wherein the collet is capable of interlocking with the shell, the clampfurther including a plurality of pins and a plurality of holes; and atool for assembling the burr hole plug in the burr hole, the toolcomprising an internal lumen capable of receiving the collet, aplurality of ribs capable of engaging the plurality of slots on thecollet to rotate the collet to cause the collet to interlock with theshell, and a plurality of pins capable of engaging the plurality ofholes on the clamp to rotate the clamp to cause the plurality of pins ofthe clamp to engage the plurality of slots on the shell.
 40. A method ofassembling the burr hole plug in the burr hole formed in the skull,comprising: inserting the medical device into the burr hole; placing theshell and the collet into the burr hole, such that the collet surroundsthe medical device; and rotating the clamp to interlock the clamp withthe shell and compress the collet, thereby securing the medical device.41. The method of claim 40, further comprising rotating the collet tointerlock the collet to the shell.
 42. The method of claim 40, furthercomprising mounting the shell to the skull.